Philippe Stenstrom

What are the memory sources of dreaming

Investigators since Freud have appreciated that memories of the people, places, activities and emotions of daily life are reflected in dreams but are typically so fragmented that their predictability is nil. The mechanisms that translate such memories into dream images remain largely unknown. New research targeting relationships between dreaming, memory and the hippocampus is producing a new theory to explain how, why and when we dream of waking life events.

Immediate and delayed incorporations of events into dreams: further replication and implications for dream function

The incorporation of memories into dreams is characterized by two types of temporal effects: the day‐residue effect, involving immediate incorporations of events from the preceding day, and the dream‐lag effect, involving incorporations delayed by about a week. This study was designed to replicate these two effects while controlling several prior methodological problems and to provide preliminary information about potential functions of delayed event incorporations. Introductory Psychology students were asked to recall dreams at home for 1 week. Subsequently, they were instructed to select a single dream and to retrieve past events related to it that arose from one of seven randomly determined days prior to the dream (days 1–7). They then rated both their confidence in recall of events and the extent of correspondence between events and dreams. Judges evaluated qualities of the reported events using scales derived from theories about the function of delayed incorporations. Average ratings of correspondences between dreams and events were high for predream days 1 and 2, low for days 3 and 4 and high again for days 5–7, but only for participants who rated their confidence in recall of events as high and only for females. Delayed incorporations were more likely than immediate incorporations to refer to events characterized by interpersonal interactions, spatial locations, resolved problems and positive emotions. The findings are consistent with the possibility that processes with circaseptan (about 7 days) morphology underlie dream incorporation and that these processes subserve the functions of socio‐emotional adaptation and memory consolidation.

Nightmare frequency as a function of age, gender, and September 11, 2001: Findings from an Internet questionnaire.

Summary of vital statistics 2002. The City of New York. New York: Bureauof Vital Statistics, New York City Department of Health and Mental Hygiene.Sciancalepore, R., & Motta, R. W. (2004). Gender related correlates of posttraumatic stress symptomsin a World Trade Center tragedy sample. International Journal of Emergency Mental Health, 6, 15–24.Silver, R. C., Holman, E. A., McIntosh, D. N., Poulin, M., & Gil-Rivas, V. (2002). Nationwidelongitudinal study of psychological responses to September 11. Journal of the American MedicalAssociation, 288, 1235–1244.Simonds, J. F., & Parraga, H. (1982). Prevalence of sleep disorders and sleep behaviors in children andadolescents. Journal of the American Academy of Child and Adolescent Psychiatry, 21, 383–388.Smedje, H., Broman, J. E., & Hetta, J. (1999). Parents’ reports of disturbed sleep in 5–7-year-oldSwedish children. Acta Paediatrica, 88, 858–865.Tanskanen, A., Tuomilehto, J., Viinamaki, H., Vartiainen, E., Lehtonen, J., & Puska, P. (2001).Nightmares as predictors of suicide.

Sensed presence as a correlate of sleep paralysis distress, social anxiety and waking state social imagery.

Isolated sleep paralysis (ISP) is a common parasomnia characterized by an inability to move or speak and often accompanied by hallucinations of a sensed presence nearby. Recent research has linked ISP, and sensed presence more particularly, with social anxiety and other psychopathologies. The present study used a large sample of respondents to an internet questionnaire (N=193) to test whether these associations are due to a general personality factor, affect distress, which is implicated in nightmare suffering and hypothesized to involve dysfunctional social imagery processes. A new measure, ISP distress, was examined in relation to features of ISP experiences, to self-reported psychopathological diagnosis, to scores on the Leibowitz Social Anxiety Scale and to scores on a new questionnaire subscale assessing social imagery in a variety of waking states. Three main results were found: (1) ISP experiences are only weakly associated with a prior diagnosis of mental disorder, (2) sensed presence during ISP is associated preferentially with ISP distress, and (3) ISP distress is associated with dysfunctional social imagery. A general predisposition to affective distress may influence the distress associated with ISP experiences; overly passive social imagery may, in turn, be implicated in this affect distress influence.

Sleep‐dependent consolidation of face recognition and its relationship to REM sleep duration, REM density and Stage 2 sleep spindles

Face recognition is a highly specialized capability that has implicit and explicit memory components. Studies show that learning tasks with facial components are dependent on rapid eye movement and non‐rapid eye movement sleep features, including rapid eye movement sleep density and fast sleep spindles. This study aimed to investigate the relationship between sleep‐dependent consolidation of memory for faces and partial rapid eye movement sleep deprivation, rapid eye movement density, and fast and slow non‐rapid eye movement sleep spindles. Fourteen healthy participants spent 1 night each in the laboratory. Prior to bed they completed a virtual reality task in which they interacted with computer‐generated characters. Half of the participants (REMD group) underwent a partial rapid eye movement sleep deprivation protocol and half (CTL group) had a normal amount of rapid eye movement sleep. Upon awakening, they completed a face recognition task that contained a mixture of previously encountered faces from the task and new faces. Rapid eye movement density and fast and slow sleep spindles were detected using in‐house software. The REMD group performed worse than the CTL group on the face recognition task; however, rapid eye movement duration and rapid eye movement density were not related to task performance. Fast and slow sleep spindles showed differential relationships to task performance, with fast spindles being positively and slow spindles negatively correlated with face recognition. The results support the notion that rapid eye movement and non‐rapid eye movement sleep characteristics play complementary roles in face memory consolidation. This study also raises the possibility that fast and slow spindles contribute in opposite ways to sleep‐dependent memory consolidation.